The invention relates to a wheelchair braking system. More particularly, the invention relates to a system for automatically preventing the wheels of a wheelchair from moving when the passenger is not fully seated in the wheelchair, thus preventing the wheelchair from moving suddenly while the passenger is in the process of sitting down or getting up from the wheelchair.
Standard wheelchairs have two large wheels which are attached on the sides of the wheelchair. These wheels are typically mounted in a manner which maximizes freedom of movement, to facilitate low effort mobility for the passenger seated in the wheelchair. However, having freely moving wheels is not always advantageous. When the passenger is getting up from the wheelchair, or sitting down, it is highly desirable that the wheelchair provide some degree of xe2x80x9csure footingxe2x80x9d for the passenger. The passenger relies on the wheelchair to balance themselves while getting up and sitting down.
Frequently, the wheelchair does not provide the needed balance, but instead rolls backward just as the passenger shifts their weight toward the wheelchair. Thus, the end result is typically a fall. The fall can cause severe injury, especially if the passenger hits their head on the chair on the way down. Often the passenger is using the wheelchair because of an injury. Thus, a fall therefrom can aggravate existing injuries, prevent them from healing correctly, or even cause new injuries.
To prevent such mishaps, some wheelchairs have a manual brake provided. U.S. Pat. No. 5,379,866 to Pearce et al. discloses a light-weight wheel assembly and static brake for wheelchairs. This manual brake allows the passenger to lock the wheels before sitting down or getting up from the wheelchair. However, the manual brake is only effective in preventing injury if the passenger remembers to set it. Further, many people who use wheelchairs suffer from diminished mental capacity. These people often forget to set the brake, and then fall when they try to get up from the wheelchair.
U.S. Pat. No. 5,358,266 to Roth et al. discloses a wheelchair electric brake and pedal safety kit. A wheelchair braking system is disclosed which has an electric switch mounted within the seat for sensing the weight of the passenger, and a brake that is operated thereby. Unfortunately, the device in Roth is electrically operated. Thus, it requires that the user maintain a charged battery power source in order for the brake to continue to operate properly.
U.S. Pat. No. 5,203,433 discloses an automatic braking wheelchair, which employs an arm that is directly linked between the seat and the wheel, for locking the wheel when the passenger rises from the seat. U.S. Pat. Nos. 4,733,755 to Manning and 4,623,043 to Babilas both disclose devices which seek to automatically lock the wheels when the passenger is exiting the wheelchair.
U.S. Pat. No. 6,012,555 to Duran et al. discloses a wheelchair braking system which automatically locks as the a person seated in the wheelchair starts to get up from the wheelchair, and which has a release lever which is operable by a helper standing behind the chair.
While these units may be suitable for the particular purpose employed, or for general use, they would not be as suitable for the purposes of the present invention as disclosed hereafter.
It is an object of the invention to produce a wheelchair braking system which automatically locks one or more wheels of a wheelchair, to prevent the wheelchair from rolling when a passenger is sitting down or getting up from the wheelchair. Accordingly a braking mechanism is provided which responds to weight upon the wheelchair from the passenger, and will lock the wheel attached thereto when the relative weight upon the wheelchair seat indicates that the passenger is not fully seated.
It is another object of the invention to produce a wheelchair braking system which adapts onto any standard wheelchair. Accordingly a system is provided which is easily attachable by simply removing the wheels mounting the braking system to the frame and reattaching the wheels.
It is yet another object of the invention to provide a wheelchair braking system which is constructed for reliability, and requires only minimal maintenance. Accordingly, a fully mechanical system is provided which does not require batteries or any other source of electrical power to operate.
It is a further object of the invention to provide a wheelchair braking system which engages to stop movement of the wheels, and then leaves very little xe2x80x9cplayxe2x80x9d within the wheels, so that once the locking system is engaged the wheels are only capable of moving a few inches forward or backward. Accordingly, braking is accomplished by engaging a foremast with the teeth of a sprocket gear. Depending on the number of teeth in the sprocket gear, play can be easily minimized to approximately ten degrees.
It is a still further object of the invention that the brake can be manually disengaged by a person helping the passenger. Accordingly, a manual release lever is provided, which extends rearward from the braking housing, so that a helper standing behind the wheelchair can easily release the brake when they are holding the chair for a person sitting down or getting up from the wheelchair.
The invention is a wheelchair braking system, for use on a wheelchair having a frame and a pair of wheels, comprising an outer plate assembly, an inner plate assembly, and an axle assembly attached to one of the wheels. The axle assembly is supported by the outer plate assembly. The axle assembly has a sprocket gear comprising a plurality of sprocket teeth. The outer plate assembly is pivotally mounted to the inner plate assembly and is capable of controlled vertical motion with respect thereto. A spring is located between the inner plate assembly and outer plate assembly, such that weight upon the wheelchair compresses the spring and allows the outer plate assembly to move upward with respect to the inner plate assembly. A foremast assembly having a foremast block is mounted to the inner plate assembly such that when the outer plate assembly is lowered sufficiently with respect to the inner plate assembly, foremast teeth thereof engage the sprocket teeth and stop the sprocket gear from rotating. Thus, when weight upon the wheelchair is reduced when a passenger gets up from the wheelchair, the outer plate assembly moves downward with respect to the inner plate assembly, bringing the foremast teeth into contact with the sprocket gear, and braking the wheels. A manual release lever extends rearward from the housing so that a person standing behind the wheelchair can selectively operate the manual release lever to free the foremast from the sprocket gear and allow the wheels to rotate.
To the accomplishment of the above and related objects the invention may be embodied in the form illustrated in the accompanying drawings. Attention is called to the fact, however, that the drawings are illustrative only. Variations are contemplated as being part of the invention, limited only by the scope of the claims.